How Extreme is Specialization in Seed-Feeding Beetles when their Hosts are Poisonous?

Abstract

The paradigm of insect-plant research is that coevolutionary dynamics select for specialization in the interaction. The purpose of this study is to follow a population genomic method to dissect the host plant specificity of seed beetles (Acanthoscelides) on multiple varieties of the toxic legume Astragalus lentiginosus. Acanthoscelides impose direct fitness consequences on A. lentiginosus through consuming the plants\u27 offspring (seeds), thus being a primary driver for high diversification and likely coevolution. I propose that through the seed beetles\u27 imposition of antagonistic selection pressures and the resulting diversity of A. lentiginosus, populations of Acanthoscelides will have genetic association with the particular variety of host plant that they were collected from. I have examined the population genetic structure of 115 individuals from 15 varying populations found on several A. lentiginosus varieties in CA, AZ, UT, and NV. I will present the results of population genetic analyses based on molecular markers in order to assess whether there is evidence of host-associated specialization in the beetle. This study creates the opportunity to assess population dynamics of seed beetles, which impose great losses in legume crop yield each year